The exchanger that is mounted on the front surface of a motor vehicle generally constitutes part of a thermal block utilized to cool the power train components of the vehicle. The said thermal block consists of a thermal exchanger or a heat exchanger supported on a frame and louvers capable of moving between an open position and a closed position.
The said thermal block may also include another thermal exchanger, being part of an air conditioning circuit for cooling the air inside the passenger compartment.
The louvers with which the exchanger ensuring the cooling of the power train components is equipped permit the adjustment of the flow of air passing through the exchanger (in this case a radiator) and originating from the opening in the grille panel, depending on the operating conditions.
When the engine is cold, the louvers are closed in such a way as to obtain zero cooling in order for the rise in temperature of the power train to be as rapid as possible. On the other hand, when the hot power train is under heavy load, the louvers are opened in such a way as to maximize the flow of air and thus to increase the efficiency of the cooling.
It has generally been established that, when the louvers are in their closed position, the heat-transfer liquid circulating inside the heat exchanger is cooled nevertheless, the effect being to slow down the time taken by the power train components to increase in temperature.